Multilayer electronic component

ABSTRACT

In order to provide a multilayer electronic component which can reduce arrangement pitches for external electrodes, via holes filled up with conductive materials are provided in a mother laminate, which is obtained by stacking a plurality of insulating sheets with interposition of conductor films, in positions parted by cutting. The conductive materials define external electrodes of individual multilayer electronic components which are obtained by cutting the mother laminate. No specific step is required for forming the external electrodes, and characteristics of each multilayer electronic component can be efficiently measured in the state of the mother laminate.

This is a division of application Ser. No. 08/445,918, filed May 22,1995 now U.S. Pat. No. 5,604,328 which is a continuation of applicationSerial No. 08/096,719, filed on Jul. 23, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multilayer electronic componenthaving internal circuit elements arranged therein, a method ofmanufacturing the same and a method of measuring characteristicsthereof, and more particularly, it relates to an improvement in a modeof forming external electrodes in a multilayer electronic component.

2. Description of the Background Art

A multilayer electronic component, which is represented by a multilayercapacitor, a multilayer inductor, a multilayer circuit board or amultilayer composite electronic component, for example, comprises alaminate which is obtained by stacking a plurality of insulating sheetswith interposition of internal circuit elements such as conductor filmsand/or resistor films. The insulating sheets are typically prepared fromceramic sheets.

FIG. 15 is a perspective view showing the appearance of a conventionalmultilayer electronic component 1. The multilayer electronic component 1comprises a laminate 2 which is obtained by stacking a plurality ofinsulating sheets with interposition of internal circuit elements (notshown). The laminate 2 is provided on its four side surfaces, forexample, with external electrodes 3 respectively. These externalelectrodes 3 are electrically connected with the internal circuitelements which are located in the interior of the laminate 2. Theexternal electrodes 3 are formed by applying proper metal paste tospecific positions of the respective side surfaces of the laminate 2,and parts of the external electrodes 3 necessarily extendcircumferentially on upper and lower surfaces of the laminate 2 at thistime.

FIG. 16 is a perspective view showing the appearance of another type ofconventional multilayer electronic component 4. This multilayerelectronic component 4 also comprises a laminate 5 which is obtained bystacking a plurality of insulating sheets with interposition of internalcircuit elements (not shown). The laminate 5 is provided on its fourside surfaces, for example, with external electrodes 6 which areelectrically connected with the internal circuit elements. Theseexternal electrodes 6 are provided by dividing through holes 7, as shownby phantom lines in FIG. 16. Namely, a mother laminate is so preparedthat a plurality of multilayer electronic components 4 can be obtainedwhen the same is cut along prescribed cutting lines. The through holes 7are formed in this mother laminate so that conductor films are formed oninner peripheral surfaces thereof for defining the external electrodes6, and the mother laminate is thereafter cut to divide the through holes7. Also in such a multilayer electronic component 4, parts of theexternal electrodes 6 extend circumferentially on upper and lowersurfaces of the laminate 5, due to the method of forming the conductorfilms for defining the external electrodes 6.

These multilayer electronic components 1 and 4 are surface-mounted onproper circuit boards through the external electrodes 3 and 6, in theform of chips.

In both of the aforementioned multilayer electronic components 1 and 4,however, the external electrodes 3 and 6 are formed to extend toward theupper and lower surfaces of the laminates 2 and 5. When other componentsare mounted on the upper and/or lower surface(s) of such multilayerelectronic components 1 and 4 to be composited with the same, therefore,areas capable of mounting such components are restricted.

Further, the parts of the external electrodes 3 and 6 extending towardthe upper and lower surfaces of the laminates 2 and 5 inhibit reductionof arrangement pitches for the external electrodes 3 and 6. In addition,it is relatively difficult to form such parts of the external electrodes3 and 5 in constant sizes and shapes, and this also inhibits reductionof the arrangement pitches for the external electrodes 3 and 6.

Particularly in the multilayer electronic component 4 shown in FIG. 16,it is difficult to reduce the diameters of the through holes 7, whichare formed by a drill, below 0.3 mm, and this also restricts thearrangement pitches for the external electrodes 6. Further, the drillfor forming the through holes 7 has a relatively short life, leading toincrease in cost.

In the multilayer electronic component 1 shown in FIG. 15, on the otherhand, the external electrodes 3 are formed on the four side surfaces ofthe laminate 2 respectively and hence it is necessary to carry out atleast application of the metal paste onto the respective side surfacesindependently of each other. As the result, the number of steps forforming the external electrodes 3 is increased.

On the other hand, it is necessary to measure characteristics of themultilayer electronic components 1 and 4 at least in advance ofshipping. In both of the multilayer electronic components 1 and 4,however, the characteristics cannot be measured unless the same arebrought into states of chips in principle. In the multilayer electroniccomponent 1 shown in FIG. 15, measurement of the characteristics isenabled after formation of the external electrodes 3. Also in the caseshown in FIG. 16, the characteristics of each multilayer electroniccomponent 4 cannot be measured in the stage of the mother laminate. Suchmeasurement of the characteristics is enabled only when the motherlaminate is cut to divide the through holes 7.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide amultilayer electronic component which can reduce arrangement pitches forexternal electrodes, and a method of manufacturing the same.

Another object of the present invention is to provide a characteristicmeasuring method which can efficiently measure characteristics of aplurality of multilayer electronic components.

A multilayer electronic component according to the present inventioncomprises a laminate which is obtained by stacking a plurality ofinsulating sheets with interposition of internal circuit elements, andexternal electrodes which are formed on outer surfaces of the laminateto be electrically connected with the internal circuit elements. Theexternal electrodes are formed by exposing at least side portions of viaholes, which are provided in the insulating sheets and coated withconductive materials, by cutting the insulating sheets.

A method of manufacturing a multilayer electronic component according tothe present invention comprises a step of preparing a mother laminate,which is to be cut along prescribed cutting lines for obtaining aplurality of multilayer electronic components, being obtained bystacking a plurality of mother insulating sheets with interposition ofinternal circuit elements for the respective multilayer electroniccomponents to distribute the internal circuit elements in regions partedby the cutting lines and having via holes, coated with conductivematerials being electrically connected with the internal circuitelements, provided in positions to be exposed on cut surfaces by cuttingalong the cutting lines, and a step of cutting the mother laminate alongthe cutting lines.

A method of measuring characteristics of a multilayer electroniccomponent according to the present invention comprises a step ofpreparing a mother laminate, which is to be cut along prescribed cuttinglines for obtaining a plurality of multilayer electronic components,obtained by stacking a plurality of mother insulating sheets withinterposition of internal circuit elements for the respective multilayerelectronic components to distribute the internal circuit elements inregions parted by the cutting lines and provided with via holes, coatedwith conductive materials being electrically connected with the internalcircuit elements, in positions to be exposed on cut surfaces by cuttingalong the cutting lines, a step of forming grooves in the motherlaminate along the cutting lines thereby exposing at least the via holeson inner side surfaces of the grooves, and a step of measuringcharacteristics of each multilayer electronic component while treatingthe via holes being exposed on the inner side surfaces of the grooves asexternal electrodes.

The configuration of the multilayer electronic components provided inthe aforementioned characteristic measuring method, i.e., an assembly ofthe multilayer electronic components consisting of the mother laminateprovided with the grooves, can be shipped in this state.

According to the inventive multilayer electronic component, the externalelectrodes are provided by exposing at least side portions of the viahole which are coated with conductive materials. In this case, the viaholes can be readily formed in small diameters by punching with noemployment of a drill, whereby arrangement pitches for the externalelectrodes can be reduced. Further, it is possible to avoid increase incost resulting from a short life of a drill since it is not necessary toemploy such a drill.

The external electrodes provided by the via holes require no mode offormation of extending circumferentially on at least one major surfaceof the laminate, whereby at least one major surface of the laminate canbe widely employed as a surface for mounting another component to becomposited with the same. Thus, it is possible to improve density incomponent mounting.

Since the external electrodes are provided by the conductive materialswhich are applied to the via holes, it is possible to attain relativelylarge dimensions corresponding to film thicknesses of the externalelectrodes by filling up the via holes with the conductive materials.Thus, it is possible to reduce a problem of solder leaching when themultilayer electronic component is soldered to a circuit board. Sincethe conductive materials for defining the external electrodes areembedded in parts of the via holes, it is possible to improve strengthof soldering.

According to the inventive method of manufacturing a multilayerelectronic component, the via holes coated with the conductive materialsfor providing the external electrodes are already formed in the motherlaminate so that the conductive materials are exposed to define theexternal electrodes by cutting the mother laminate, whereby no specificstep is required for providing the external electrodes.

According to the inventive method of measuring characteristics of amultilayer electronic component, further, it is possible toindependently measure characteristics of a plurality of multilayerelectronic components, which are mechanically integrated with each otherin the form of a mother laminate in a state being electricallyindependent of each other, due to formation of the grooves. Therefore,it is not necessary to handle mechanically independent multilayerelectronic components, but characteristics of a number of multilayerelectronic components can be efficiently measured by screening, forexample.

When the assembly of the multilayer electronic components consisting ofa mother laminate provided with the grooves, which is a configuration tobe subjected to the aforementioned measurement of characteristics, isshipped in this state, the user can take out the respective multilayerelectronic components from the mother laminate by simply dividing thesame along the grooves. It is to be noted that each multilayerelectronic component can be subjected to mounting with no problem inthis case since the same can be through with measurement of itscharacteristics, and the assembly of such multilayer electroniccomponents is easy to pack and handle as compared with multilayerelectronic components which are separated from each other.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the appearance of a multilayerelectronic component 10 according to an embodiment of the presentinvention;

FIG. 2 is a perspective view showing a mother laminate 14 which isprepared for obtaining the multilayer electronic component 10 shown inFIG. 1;

FIG. 3 is an enlarged perspective view illustrating grooves 20 which areformed in the mother laminate 14 shown in FIG. 2 for enablingmeasurement of characteristics;

FIG. 4 is a perspective view showing the appearance of a multilayerelectronic component 10a according to another embodiment of the presentinvention;

FIG. 5 is a sectional view illustrating the multilayer electroniccomponent 10a shown in FIG. 4 which is mounted on a circuit board 31;

FIG. 6 is a sectional view illustrating a terminal member 33 which ismounted on the multilayer electronic component 10a shown in FIG. 4;

FIG. 7 is a perspective view showing the appearance of a multilayerelectronic component 10b according to still another embodiment of thepresent invention;

FIG. 8 is a perspective view showing the appearance of a multilayerelectronic component 10c according to a further embodiment of thepresent invention;

FIG. 9 is a perspective view showing the appearance of a multilayerelectronic component 10d according to a further embodiment of thepresent invention;

FIG. 10 is a perspective view showing the appearance of a multilayerelectronic component 10e according to a further embodiment of thepresent invention;

FIG. 11 is a perspective view showing the appearance of a multilayerelectronic component 10f according to a further embodiment of thepresent invention;

FIG. 12 is a plan view showing a part of a mother laminate 14 forillustrating a further embodiment of the present invention;

FIG. 13 is a sectional view showing a cased multilayer electroniccomponent 42 according to a further embodiment of the present invention;

FIG. 14 is a sectional view showing a cased multilayer electroniccomponent 42a according to a further embodiment of the presentinvention;

FIG. 15 is a perspective view showing the appearance of a conventionalmultilayer electronic component 1; and

FIG. 16 is a perspective view showing the appearance of another type ofconventional multilayer electronic component 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a perspective view showing the appearance of a multilayerelectronic component 10 according to an embodiment of the presentinvention. While the multilayer electronic component 10 is mounted on aproper circuit board in the chip-type configuration as illustrated, FIG.1 shows the multilayer electronic component 10 in a state upwardlydirecting its surface which is faced toward such a circuit board.

The multilayer electronic component 10 comprises a laminate 11, which isformed by stacking a plurality of insulating sheets with interpositionof internal circuit elements (not shown). The laminate 11 is provided onrespective ones of its four side surfaces, for example, with externalelectrodes 12 which are exposed on outer surfaces of the laminate 11.These external electrodes 12 are electrically connected with theinternal circuit elements (not shown).

The aforementioned external electrodes 12 are formed by exposing atleast side portions of via holes, which are provided in the insulatingsheets and filled up with conductive materials, by cutting theinsulating sheets, as clearly understood from the following descriptionof a manufacturing method. The laminate 11 is provided on respectiveones of its four side surfaces, for example, with steps 13, while thereason why such steps 13 are formed is also clarified by the followingdescription of the manufacturing method.

In order to obtain the aforementioned multilayer electronic component10, a mother laminate 14 is prepared as shown in FIG. 2. The motherlaminate 14, which is to be cut along prescribed cutting lines 15 shownby one-dot chain lines to provide a plurality of multilayer electroniccomponents 10, is obtained by stacking a plurality of mother insulatingsheets 16 and a plurality of mother insulating sheets 17 withinterposition of internal circuit elements (not shown) for therespective multilayer electronic components 10 to distribute theinternal circuit elements in respective regions parted through thecutting lines 15. This mother laminate 14 is provided with via holes 19filled up with conductive materials 18 which are electrically connectedwith the internal circuit elements (not shown) in positions to bepartitioned by cutting along the cutting lines 15. The externalelectrodes 12 shown in FIG. 1 are provided by the conductive materials18 which are filled up in the via holes 19.

In order to obtain the aforementioned mother laminate 14, the followingsteps are carried out, for example. According to this embodiment, themother insulating sheets 16 and 17 are formed by ceramic sheets.

First, sheet forming is carried out by a doctor blade coater or thelike, to obtain ceramic green sheets for defining the mother insulatingsheets 16 and 17. Specific ones of these ceramic green sheets areprovided with via holes by punching or the like, in order to enableelectrical conduction through the sheets along the direction ofthickness. At this time, the ceramic green sheets for defining themother insulating sheets 16, which are located on relatively upperportions in FIG. 2, are further provided with via holes 19. Then,conductor films and/or resistor films for serving as internal circuitelements are printed on specific ones of the ceramic green sheets. Atthis time, the already formed via holes are filled up with conductivematerials, while the via holes 19 shown in FIG. 2 are filled up withconductive materials 18. When the conductor films are printed from lowersurface sides of the mother insulating sheets 16 shown in FIG. 2, it ispossible to prevent the conductive materials 18 from forming conductivelands in peripheral edge portions of the via holes 19 on upper surfacesides of the mother insulating sheets 16. It is pointed out that evensuch conductive lands are within the scope of the present invention.

Then, the aforementioned mother insulating sheets 16 and 17 are stackedwith each other and pressed. Thus, the mother laminate 14 is obtained.In this mother laminate 14, the via holes 19 provided in the respectiveones of the plurality of mother insulating sheets 16 are aligned alongthe direction of thickness, whereby the conductive materials 18 filledup in the via holes 19 are connected in series with each other.

Then, grooves 20 are formed in the mother laminate 14 along cuttinglines 15 (FIG. 2) with a dicing saw, for example, so that at least thevia holes 19 are parted, for example. With such formation of the grooves20, the via holes 19 are exposed on inner side surfaces of the grooves20, while the conductive materials 18 which are filled up in the viaholes 19 are parted so that portions enclosed by the grooves 20 fordefining individual multilayer electronic components 10 are electricallyindependent of each other. Preferably, slits 21 and 22 are formed inbottom surfaces of the grooves 20 and lower surface portions of themother laminate 14 opposite thereto respectively. Either the slits 21 or22 may be omitted.

FIG. 3 shows some conductor films 23 and 24 for serving as internalcircuit elements. This figure also shows states of the conductor films23 electrically connected with the conductive materials 18.

Then, the mother laminate 14 is fired to sinter ceramic materialsforming the mother insulating sheets 16 and 17. Thereafter surfaces ofthe mother laminate 14 are provided with conductor films and/or resistorfilms, covered with an overcoat, and coated with solder resist. Ifnecessary, the conductive materials 18 for forming external electrodes 3and other conductor films are plated.

When the aforementioned steps are completed, the plurality of multilayerelectronic components 10 included in the mother laminate 14 are soelectrically independent of each other that it is possible to measurecharacteristics of each multilayer electronic component 10 whiletreating the conductive materials 18 provided in the respective portionsof the via holes 19 parted by the grooves 20 as external electrodes.

After the characteristics are measured, other electronic components aremounted on those of the multilayer electronic components 10 which aredetermined as nondefective, to be composited with the same. The stepsheretofore described can be efficiently carried out in the state of themother laminate 14. The multilayer electronic components 10 may beshipped in this stage.

Then, the mother laminate 14 is completely cut along the cutting lines15 (FIG. 2), i.e., the grooves 20 (FIG. 3), in order to obtain aplurality of multilayer electronic components 10 which are mechanicallyindependent of each other. Such cutting is readily attained by dividingthe mother laminate 14 like a chocolate bar along the grooves 20. Theaforementioned slits 21 and 22 facilitate such division.

Thus, the multilayer electronic component 10 shown in FIG. 1 isobtained. As understood from the above description, the steps 13 resultfrom the formation of the aforementioned grooves 20. When the laminate11 is classified into upper and lower half portions through a boundarysurface corresponding to the positions of the steps 13, the externalelectrodes 12 are exposed only on the upper half portion.

Then, the multilayer electronic component 10 is covered with a case atneed. This case is adapted to cover other components which may bemounted on a lower surface of the multilayer electronic component 10appearing in FIG. 1. This case is described later with reference toFIGS. 13 and 14.

While the present invention has been described with reference to theembodiment shown in FIGS. 1 to 3, various modifications are availablewithin the scope of the present invention.

While the external electrodes 12 shown in FIG. 1 are formed to beexposed not only on the side surfaces of the laminate 11 but on theupper surface appearing in FIG. 1, such external electrodes 12a may beformed to be exposed only on side surfaces of a laminate 11 in amultilayer electronic component 10a shown in FIG. 4, for example.Referring to FIG. 4, elements corresponding to those shown in FIG. 1 aredenoted by similar reference numerals, to omit redundant description.

According to the multilayer electronic component 10a shown in FIG. 4, itis possible to widely utilize not only a lower surface of the laminate11 appearing in this figure but the upper surface as mounting surfacesfor other components to be composited with this component 10a, with nointerference by the external electrodes 12a. In order to obtain such amultilayer electronic component 10a, mother insulating sheets having novia holes 19 for forming external electrodes may be employed to formsome of those located on an upper portion of the mother laminate 14 in astage of manufacturing the mother laminate 14 shown in FIG. 2.

When the aforementioned multilayer electronic component 10a is placed ona circuit board 31 as shown in FIG. 5, a gap is defined between thecircuit board 31 and each external electrode 12a. In order to mount themultilayer electronic component 10a on the circuit board 31 in such astate, a solder fillet 32 is advantageously employed in order toelectrically connect the external electrode 12a with a conductive land(not shown) on the circuit board 31.

Alternatively, a terminal member 33 of a metal may be mounted on eachexternal electrode 12a of such a multilayer electronic component 10a, asshown in FIG. 6.

The external electrodes 12 of the mode shown in FIG. 1 may be mixed withthe external electrodes 12a of the mode shown in FIG. 4 in a singlemultilayer electronic component.

While the via holes 19 for providing the external electrodes 12 havecircular sections in the embodiment shown in FIGS. 1 to 3, such sectionsmay be changed to other forms such as rectangular shapes. Further, asingle external electrode may be provided by a plurality of via holeswhich are partially overlapped with each other in section, or by a viahole long from side to side, in order to expose such external electrodesin wider areas.

The grooves 20 and the slits 21 and 22 may be formed after firing of themother laminate 14. If no efficiency in formation of the conductorfilms/resistor films on the fired laminate 14 or plating orcharacteristic measurement is taken into consideration, the motherlaminate 14 may be cut along the cutting lines 15 before firing, so thatthe multilayer electronic components 10 are fired in mechanicallyseparated states. Further, the mother laminate 14 may be cut along thecutting lines 15 immediately after firing, through no stage of formingthe grooves 20.

The conductive materials 18 to be filled up in the via holes 19 may notbe applied simultaneously with printing of the conductor films, but thevia holes 19 may be filled up with metal paste in another step. In thiscase, it is also possible to simultaneously fill up the conductivematerials 18 in the plurality of via holes 19 being aligned in serieswith each other in the plurality of mother insulating sheets 16 whichare stacked with each other.

The insulating sheets are not restricted to ceramic sheets, but may beprepared from other materials.

As shown in FIG. 7, further, external electrodes 12b of a multilayerelectronic component 10b may be provided by conductive materials whichare layered on inner peripheral surfaces of the via holes 19 (FIGS. 2and 3). In this case, the external electrodes 12b define cavities onouter surfaces thereof.

The present invention is not restricted to a multilayer electroniccomponent having a plurality of external electrodes all of which areformed on the basis of via holes, but is also applicable to a multilayerelectronic component including some external electrodes which are formedby another method.

As shown in FIG. 8, for example, a multilayer electronic component 10cmay have some external electrodes 12 which are formed on the basis ofvia holes and other external electrodes, such as shielding electrodes25, for example, which are formed by another method. In formation of thegrooves 20 as shown in FIG. 3, for example, grooves 20 having inner sidesurfaces to be provided with such shielding electrodes 25 are firstprepared so that metal paste is filled up in these grooves 20 byinjection. Finally the grooves 20 are cut again to part conductivematerials provided by the metal paste, thereby forming the shieldingelectrodes 25. These shielding electrodes 25 are often electricallyconnected with ground-side internal circuit elements (not shown) of thelaminate 11.

The aforementioned shielding electrodes 25 may alternatively be formedon the basis of via holes, as a matter of course. In this case, the viaholes are formed by slots longitudinally extending along the shieldingelectrodes 25. Such shielding electrodes 25 may be formed after theindividual multilayer electronic components 10c are obtained.

As shown in FIG. 9, shielding electrodes 25a may be formed to extenddownwardly beyond steps 13, in order to improve shielding performance.Such shielding electrodes 25a can be formed by any of the followingmethods, for example:

(a) A method of forming the overall shielding electrodes 25a on thebasis of via holes.

(b) A method of forming only lower half portions of the shieldingelectrodes 25a beyond the steps 13 on the basis of via holes whileforming upper half portions by filling up the grooves 20 shown in FIG. 3with metal paste.

(c) A method of forming upper half portions of the shielding electrodes25a by filling up the grooves 20 with metal paste, obtaining individualmultilayer electronic components 10a, and thereafter forming lower halfportions.

(d) A method of forming upper half portions of the shielding electrodes25a on the basis of via holes, obtaining individual multilayerelectronic components 10d, and thereafter forming lower half portions.

(e) A method of forming the overall shielding electrodes 25a afterobtaining individual multilayer electronic components 10d.

When the method (a) or (b) is employed among the aforementioned methodsof forming the shielding electrodes 25a, the plurality of multilayerelectronic components 10d are electrically connected with each otherthrough the shielding electrodes 25a and not yet completely electricallyindependent of each other in a stage provided with the grooves 20 shownin FIG. 3. However, no hindrance is caused in measurement ofcharacteristics of the individual multilayer electronic components 10din the aforementioned state of the mother laminate 14 when the shieldingelectrodes 25a are adapted to serve as a common earthed electrode insuch characteristics measurement.

In the multilayer electronic component 10d shown in FIG. 9, an areawhich is provided on the lower surface of the laminate 11 for mountingother components may be narrowed by the shielding electrodes 25a. Inorder to avoid such inconvenience, shielding electrodes 25b may beformed not to reach a lower surface of a laminate 11 provided in amultilayer electronic component 10e, as shown in FIG. 10.

In relation to each mode of formation of the shielding electrodes 25,25a and 25b shown in FIGS. 8 to 10, the upper half portion(s) of theshielding electrode(s) may be formed on only one or three side surfacesof the laminate 11. The lower half portions of the shielding electrodesmay be formed on three or four side surfaces of the laminate 11.Although only the shielding electrodes 25 corresponding to upper halfportions are provided in FIG. 8, only shielding electrodes correspondingto lower half portions may alternatively be provided.

As shown in FIG. 11, further, a shielding electrode 25c may be providedon a multilayer electronic component 10f to cover only a part of oneside surface of a laminate 11 along the cross direction.

In each of the aforementioned embodiments, each via hole 19 is so partedas to define external electrodes 12 for respective ones of twomultilayer electronic components 10. When the width of each groove 20shown in FIG. 3 occupies a considerable part along the diameter of eachvia hole 19, however, a single via hole 19a may be adapted to define asingle external electrode, as shown in FIG. 12. FIG. 12 shows parts ofthe via holes 19a before formation of the groove 20 with two-dot chainlines.

FIG. 13 is a sectional view showing a multilayer electronic component 42which is covered with a case 41.

A laminate 43 provided in the multilayer electronic component 42 hassteps 44, and external electrodes 45 are formed under these steps 44.Some electronic components 46 are mounted on an upper surface of thelaminate 43 appearing in FIG. 13 for compositing this multilayerelectronic component 42. The case 41 is made of a metal. This case 41 isprovided with steps 47 in conformity with side surfaces of the laminate43, and soldered to the external electrodes 45, for example.

FIG. 14 shows another multilayer electronic component 42a which iscovered with a case 41a. Referring to FIG. 14, elements corresponding tothose shown in FIG. 13 are denoted by similar reference numerals, toomit redundant description.

Referring to FIG. 14, a laminate 43 which is provided in the multilayerelectronic component 42a is formed not only with steps 44 but withfurther steps 48. On the other hand, the case 41a is provided with steps49 which are engaged with the steps 48. The steps 49 of the case 41a areso engaged with the steps 48 of the laminate 43 that the case 41a isfurther strongly mounted on the laminate 43. Even if force is applied tothe upper surface of the case 41a to downwardly press the same, inparticular, the case 41a is not disengaged from the external electrodes45. Such force of downwardly pressing the case 41a is often applied froma vacuum suction chuck (not shown) which sucks the multilayer electroniccomponent 42a toward the upper surface of the case 41 for holding thesame. The steps 48 can be formed on the laminate 43 by a method similarto that for the steps 44. Namely, grooves similar to the grooves 20 maybe formed from below in positions corresponding to the grooves 20 in thestage of the mother laminate 14 shown in FIG. 3.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the scopeof the present invention being limited only by the terms of the appendedclaims.

What is claimed is:
 1. A multilayer electronic component for mounting ona surface of a substrate with external electrodes of said multilayerelectronic component being soldered to the substrate, the multilayerelectronic component comprising:a laminated ceramic sintered body havinga plurality of stacked insulating sheets with internal circuit elementsinterposed therebetween, said ceramic sintered body having first andsecond opposite major surfaces and side surfaces connecting said majorsurfaces with each other; said side surfaces having a step portionextending parallel to said major surfaces so as to define a firstportion of said ceramic sintered body that includes said first majorsurface, and a second portion of said ceramic sintered body thatincludes said second major surface; and external electrodes provided onouter surfaces of said ceramic sintered body and electrically connectedwith said internal circuit element, said external electrodes beingexposed only on said first portion of said ceramic sintered body forbeing soldered to a substrate, wherein said external electrodes areformed from midway of said side surface on said first portion until justbefore said step portion.
 2. A multilayer electronic component formounting on a surface of a substrate with external electrodes of saidmultilayer electronic component being soldered to the substrate, themultilayer electronic component comprising:a laminated ceramic sinteredbody having a plurality of stacked insulating sheets with internalcircuit elements interposed therebetween, said ceramic sintered bodyhaving first and second opposite major surfaces and side surfacesconnecting said major surfaces with each other; said side surfaceshaving a step portion extending parallel to said major surfaces so as todefine a first portion of said ceramic sintered body that includes saidfirst major surface, and a second portion of said ceramic sintered bodythat includes said second major surface; and external electrodesprovided on outer surfaces of said ceramic sintered body andelectrically connected with said internal circuit element, said externalelectrodes being exposed only on said first portion of said ceramicsintered body for being soldered to a substrate, wherein said externalelectrodes are formed from said first major surface until just beforesaid step portion.
 3. A component as in claim 2, wherein said externalelectrodes are exposed at said first major surface.
 4. A component as inclaim 3, wherein said first major surface is for being mounted on saidsubstrate with said external electrodes being soldered to the substrate.5. A component as in claim 3, wherein said insulating sheets include viaholes, conductive materials being filled in said via holes, and saidexternal electrodes being exposed side portions of said conductivematerials in said via holes.
 6. A component as in claim 3, wherein saidinsulating sheets include via holes, conductive materials being layeredon inner peripheral surfaces of said via holes, and said externalelectrodes being exposed side portions of said conductive materials insaid via holes.
 7. A component as in claim 2, wherein said first majorsurface is for being mounted on said substrate with said externalelectrodes being soldered to the substrate.
 8. A component as in claim2, wherein said insulating sheets include via holes, conductivematerials being filled in said via holes, and said external electrodesbeing exposed side portions of said conductive materials in said viaholes.
 9. A component as in claim 2, wherein said insulating sheetsinclude via holes, conductive materials being layered on innerperipheral surfaces of said via holes, and said external electrodesbeing exposed side portions of said conductive materials in said viaholes.
 10. A component as in claim 1, wherein said first major surfaceis for being mounted on said substrate with said external electrodesbeing soldered to the substrate.
 11. A component as in claim 1, whereinsaid insulating sheets include via holes, conductive materials beingfilled in said via holes, and said external electrodes being exposedside portions of said conductive materials in said via holes.
 12. Acomponent as in claim 1, wherein said insulating sheets include viaholes, conductive materials being layered on inner peripheral surfacesof said via holes, and said external electrodes being exposed sideportions of said conductive materials in said via holes.
 13. Amultilayer electronic component for mounting on a surface of a substratewith external electrodes of said multilayer electronic component beingsoldered to the substrate, the multilayer electronic componentcomprising:a laminated ceramic sintered body having a plurality ofstacked insulating sheets with internal circuit elements interposedtherebetween, said ceramic sintered body having first and secondopposite major surfaces and side surfaces connecting said major surfaceswith each other; said side surfaces having a step portion extendingparallel to said major surfaces so as to define a first portion of saidceramic sintered body that includes said first major surface, and asecond portion of said ceramic sintered body that includes said secondmajor surface; and external electrodes provided on outer surfaces ofsaid ceramic sintered body and electrically connected with said internalcircuit element, said external electrodes being exposed only on saidfirst portion of said ceramic sintered body for being soldered to asubstrate, wherein said external electrodes extend from a point spacedfrom said first major surface on said side surface of said firstportion, to just before said step portion.
 14. A component as in claim13, wherein said first major surface is for being mounted on saidsubstrate with said external electrodes being soldered to the substrate.15. A component as in claim 13, wherein said insulating sheets includevia holes, conductive materials being filled in said via holes, and saidexternal electrodes being exposed side portions of said conductivematerials in said via holes.
 16. A component as in claim 13, whereinsaid insulating sheets include via holes, conductive materials beinglayered on inner peripheral surfaces of said via holes, and saidexternal electrodes being exposed side portions of said conductivematerials in said via holes.